function add(parentName){
	var str =  parentName;
	var id = $("table > tbody >tr:last").attr("id") * 1 + 1;
	var element = $("<tr id="+id+"><td>"+id+"</td><td><input type='text' class='form-control' name='userName' value='' size='5'/></td><td></td><td></td></tr>");
	
	$("table > tbody >tr:last").after(element);
}